To wireless



"Dec. 25, 1928; 1,696,895 G. W. PICKARD HIGH TENSION ELECTRICAL CONDENSER Filed June 26, I924 29 @WITORNEY Patented Dec. 25, 1928.

UNITED STATES PATENT OFFICE.

GREENLEAF WHITTIER PICKARD, OF NEWTON CENTER, MASSACHUSETTS, ASSIGNOR TO WIRELESS SPECIALTY APPARATUS COIVIPANY, OF BOSTON, MASSACHUSETTS, A

CORPORATION OF NEW YORK.

HIGH-TENSION ELECTRICAL CONDENSER.

Application filed June 26,

This invention relates to improvements in high tension electrical condensers of the sheet-stack type, more particularly those wherein the stack comprises a plurality of serially-connected sections whereby the stack has a high potential difference across its ends.

An objectof the invention is to provide a structure whereby the stack is clamped between metal clamping means-applied to its ends, yet all parts of the stack of high potential difference are provided with better insulation than is practicable where a metal casing is employed for a stack of this type.

- The invention consists of the improvements substantially as shown and described in the drawings, of which Figure l is an assembly shown generally in central longitudinal section but with certuin parts shown in elevation; i

Fig. 2 is a plan of the enclosing casing of the assembly of Fig. l; Y

' Figs; 35 are elevations of parts shown inassemhly at the top ofFig. 1, F 3 being an elevation of a heat-radiating terminal at one end of the stack and casing,- Fig. 4. being an elevation of a metal casing end, and Fig. 5

being an adjustable clamping member; I

Fig. 6 is an elevation of the metal parts of the lower end of Fig. l. 1

Heretofore it has been customary, with stacks of this type. consisting of seriallyconnected sections, to enclose the stack. in a wax enibedment itself enclosed in a metal casing constituting the low potential terminal or grounded sideoft-he stack. Vhile such casing of metal provides a-practical construction, yet it involves practical difliculties in properly insulating the high potential portions of the stack, and the high potential terminal thereof, from the metal of the cas ing. In accordancewit-h this invention, the metal parts and terminals atthe opposite ends of the stack, which have high potential difference, areinsulated from one another by an insulating casing extending from end to end of the stack and mechanically connected with the metal parts at the two ends of the stack. p

The stack S itself is shown in assembly in Fig. 1 and is in the usual form of stacks of the serially-connected section type, the sevcral sections being shown as insulated from one another by separators E, and the pro- 1924. Serial No. 722,431.

jet-ting foils F of each section being shown 4 as connected to the projecting foils of like polarity of an adjacent section.

lnl igs. 1 and 2 is shown a casing I of insulating material such as inicarta, bakelite .or other insulating material, this being preferably in tubular form with open ends as shown and constituting a'continuous circular side wall of the casing enclosing the wax embedm'ent 7 whiclrsurroundsstack S between the metal endplate s of the casing. The thickness of the WalLoftubular casing I and theinsulating.iriateirialpf whichthetube is composed aresucli -as tolprovicle sufficient Strength to withstand the tensile istrain to which the. tube is subjected, as will be described. iCasi n I maybeftubular in other cross sections t an n mas-f 's 1 ii ti be l l ew ii t'th 1 part of Fig. I'i's 'elos'ed by'ia'inetal end memer shown 6, inlelejation at the left half, and insectiop latitlie rightihalf; This member and thoseshowri'in Figsi'3 5'.'pref- .erably consist of aliiiniii'uni for' lightness, strength jand electrical conductance. The metalbottom niember of Figi- 6 comprises an engiyzlosi ng and -,c 1ampi iig: 1atei\*, and other partscast integ jahtlierewith as follows he'fian e t'app''diwith s15: equally spacedlioles, .-wliich. r egister with holes H o'finsulating tiibe I bf' both sets of holes receiving'the'scretjsjQ (Fig. 1)]to se- :cure..tube I and endgclanip'in'gfmember together, the tube lit-tingi as'shown. in Fig. 1, against flange G and the iip'perj surface of the peripheral portion of end plate N. The end member ofjF/(j al a" coinprises' the heat-radiating fi nslor vanes a threaded terminal T for' theiattatilinicntilofan external lead to the coiideiiiserg As shown in Fig. 1.'an

internal lead I), which consists ofa thi'n, flexible copper strip, compressed between the stack andtheen'dplate connected to the lowermost section of theist'ack atone end, as by fusing t0.a projectiiig'icopper foil of that section; and said strip is screwed at J in good electrical and thermal connection with end plateN to connect that endof the stack with the terminal post T. and vanes R. This lead L is thereby'electrically and thermally connectedto plate N, preferably before the bottomtmember of Fig.6 is screwed into place at the lower part of tube I. Stack S, resting on the bottom plateN, is. assembled with tube I, anil screws C pass throu h the registering holes in both said'nienibers h 'and I. The end parts of this condenser mayhe held to the insulating easing, i. e., secured 5 against being forced off the end-or ends of the insulating raising, in various ways other than that herein disclosed.

The other end of the stack provided with a similar copper strip lead lf connected to the uppermostsection of st-aek'S as by soldering to anensl copper foil of that section, and screwed at. J to the clamp plate I (Figs. 1 and 5). 'This copper strip-L may be several inchesdongso that-Iit-L naybe connected com 'eni ently1bot h to the end section of stm-k to. elamping plixtejP when said stack and plateibefoite asseifiblywithltube I are separated from ;one,'.zinother; .and when the C( nect ions oft-he ends of strip;L aremade, the latterinay. be folded accordion-wise (Fig. the bringiri together of the stack and plate P inside tithe ,I. 'Preferably cast mtegral 'withQ-PlateP is aeylindrieal hossD whiqlris formedwith .21 spline 'A fora inch square lieyi the other half of the spline being joi r'ned at A in bossB'a'nd plate of Fig. .4. .iThis.iarrangemntprevents the turning of plate P when it is. ioreedagainst the steel; .by. the; member fof 'Fig. 3 to be d e'scr ibetl. Thus far, 'theistack S has been assembled with the end jcastirigofi-Eigltl and with the clamping iiiem berll ofFigI .5; all; three being surrounded byQt-he insulating'tnhe'I; tube I and the low er' metal end being. secured, together by thelsixi loiwer. screws C; the'wax Vt of Fig. .1 not yethavinglbeen, emplaeed. Next, the other end plate l 2 (Fig. 4) is put in place, (Q n {t p of. ela'n lp ii' g plate'I?) its upper external y ith'rea'c 'ed integral .boss B being .f'ormed holldw. to be slipped over the boss D of clamping plate; P of Fig. 5 nowresting on to i'eflstaelr S. This end. plate 'N is secured to tnbhlar irisnlatingv casing I by screws C the tube-.I fitting against end. )late N and fian e G in the same way as at. the other end of tne easing.

Next, theheat-radiatingterminal shown in Fig.3,iiiternali threaded at B, is screwed over-boss B of easing-end N. This terminal .member of Fig. '3 coiiipri sesihea t-radiatin fins or yanes Bandathreaded ter iiinal'post .T; t-lleiup'p'enpart of the casting being solid internally above the hollow threaded portion .13. Asthis terminal member of Fig. 3 is screwed'downlon boss 15p: end plateN the interior's'olid portion engages the top'of boss Dots-lumping platePbfFig. 5, and forces said plateagainst st {:li S the stack hearing atits otheifl end aga-inst bottom 'clamping plate. N, Tennin'alf member vT is screwed ddwriiiiitil.thelinica and, foil she'etsof the entire stack are brought toget l ier in intimate contact. with one another sueeesTsli-ely under as'liigli pressure asjpraeticalile withoutdeformingthefoil strips of the stack. The wall the 1 )urpose of complete; filling the u...

of insulating tube 1 acts asihe tension na-m her of the rlampin; system. Clamping plat;- Phas sufiicient. diameter to engage. orer the entire active areaof the steel; sheets, like hql tom end member N. Preferably stark previously ha-s'heen suhjeeted to was treatment wherein molten paraliin wax has been allowed to enter between the stack-sheets, and then while molten has been squeezed out by the application ofhig'h uu-chanical prr mof the order of a ton per square inch. carr mg with it all air or moisture and any other foreign matter Harmful to the condenser in service. 'l he applieat'i on of clamping; plate P in the final assembly of the condenser restores the above compressed condition of the stack and keeps out air and moisture permanently.

The clamping and terminal member "1 of F:ig. 3}is screwed downby a spanner-wrench efngagingjin th e'holes M (Fig. 3) shown in Fig. 1 'zis'o'ce upied by pins J, J. .Vhen the desi'r'ed pressure on steel: S has been attained. the' holes iii in the terminal memberare eont-inn'e'd by drilling holesK (Fig. 4)' in hossl l of the casing-end of 4. Finally; in n'gis' tering holes'M, K of Figs.3.ar.d a} respectively are driven thepins J, J of Fig 1, thereby locking the parts against rotation and maintainin; permanently thedesired high servie pressure on the'staek S.

It is contemplated to be .p raetical to employ various .forms of 'elamping means, in combination with the instilat-ing stack-easing; of thejini'entionj and it is not'ne cessai'y that the 'insnlatingeasirig be, shown; a: tension iheihb'er of the staek-clamp, as shown. or any part of the 612111111), although theusc o'f the insulatingeasi'ng as. a tension member of the.

stack-clamp is'a valuable feature of t-he'invention.

A. s sliowlriniFigs. 1 and 2, the insnlatin; lube I is formedwitli'a threaded opening' intermediatethe ends of the tube. which at this stage. ofmamrfacture is the onlyopeningg from outside to thespacebetweeh the sides stack S and the easing,-the'meti1l end niembeis entirely enclosing the open ends of insulating tube I. Through fsaid ogenin X molten jparaflin (as one of the various suitable fillers isfio\ vedinto such space to form the solidified embedment Yt around the Stack. This fivaXing -or "embedm ent of the eondenser is efi'ected'after the stack has been put under thedesired compression, and the Wax embedment serves to keep air and moisture from a= )roa'chim the sides of the staclt.

t D Since the wax contracts on, cooling,

ticnal wax will be added at. proper in through opening XQduring the period when theemhedznent is co'olingand solidifi'mg for with waxand preientii; the. fornnzliou e acksorroids in the e'mbedluent. 'lhe wa}: fills the. space. as shown, between lop end plate N and compression plate P. After the insulating embedment \V has solidified, filling the entire space between stacks and all the walls of easing I, a screw plug, preferably of insulating material, is screwed into lateral threaded opening X (Figs. 12) in order completely to seal the device. Ihis screw may be screwed into the wax embedmeut V until its outer face is flush with the outer surface of insulating tubular casing I.

Either external terminal T or T 2 may be the higher low potential tern'iinal of the condenser. Insulating casing I preferably is tubular for strength and simplicity of construction. In this device, between the two end sections of stack S there are no metal parts save the foils of the stack'aud end leads L, L; that is, the entire structure between its ends consists (with the exception of the foils and end-leads) of insulating material, including the mica or other insulatin sheets of the stack, the insulating (mica) section-separators E, thewax embe'chnent \V and the insulatiugcasing tube I. Thus there isquaximum insulation: between the metal partsv connected with the two en-dsof the stack; and as the. potential difference increases-withthe distanw from a. low poten tialend of thestack, the parts of the apparatus adjacent such higherpotential portions of the stack, consisting of insulating natgerial as they do, obviate all insulation dilficulties. As: the potentialrises at portions of the stack yet further removed from the low potential end, such portions are located in the vicinity of the metal end parts of the condenser constituting-the high potential portions'of the apparatus which are insulated by casing I. The insulating casing also provides ample leakage path or creepage dis tance between the respective'metal endportious of the device. The insulating casing I readily is made of-sufiicient strength to with? stand the tension clamping strains, withoutundue thickness of the enclosing-wall. \Vith this construction, no especial attention is re.- quired to. the matter of relative-location of the casingwall I andsectionsofstack S intermediate itsends, and .by reas'onot' the easing wall consisting of insulating material, the wall may be as close as desired to projecting stackfoils F, only a minimum of waxfilled space between the casing wall and the stack being desirable; that is, the wax embedment- W may be thin -as compared with the practice heretofore because it is employed only to seal the'stack against air and moisture, and only (in combination with the insulating casing wall) for the purpose of insulating the stack from exterior metal objects. This condenser unit by reason'of its construe.- tionread-ily can be made into units of large capacity and high voltage, and thereby is especially adapted for use in connection with carrier currents in the-art of electrical com munieatiou.

The heat-radiating vanes R and R serve to keep down the temperature of the stack during service, and act in lieu of the metal casings heretofore employed; the heat being conducted to said radiating vanes from the metal casing ends, both directly from the stack particularly by conductors L, L and also via the wax filler \V to the casin g ends. The conductors L, L'-' take heat to N and R not only from the end faces of the stack S but also from the interior of the stack by way of the armature foils F; and the clamping of L, L at J, J and between the stack and the metal parts N and P, provides good thermal connections, between the stack (inside of which the heat is generated and the heat-dissipating surfaces (as R, outside the casing. This is important in'case of use of heavy currents, because here the insulating casing portionI' is not a good heat-conductor (as were the prior inetal casings extending a ongsidc projecting foils I and therefore the only outward route here -for heat absorbed from the stack and its projecting foils F by wax I yia the wax which preferably is of small mass) to the metal end structures. Hence the leads L",'L ,'in this c or'nbination with the insulating' 'casin I, are'relied on not only as terminal leads but as the'principal means for removing heat continuously from the interior of thesta'ck'to the external heat-dissipating surfaces of the metal structures at the ends of the insulating casing." Thus as shown and described, the conductorsL, Lnot only are in good thermal contact: with the parts which theyco'nnect, but themselves are of substantial cross-sectional area relative to the in' (lividual foil-bunches, (with all of which they are connected in series) so as to permit said continuous drain of heat to both ends of the condenser from' its middle; In instances where the heat radiation is needed only at one end of the condenser, the insulating casing -maybe tubular'or box-shape with integral bottom, and without any metal parts at the bottom, save permissively' a terminal projecting from the stack through anopenin'g in the insulatingbottdm""and constituting the metal eiid structure at'thej bottom. In any instance wax filling may be omitted.

' The advantages of thisstrikinglynovel invention as a wholeare many and various and include thefollowing. In thepractical construction provided, the ends of the stack at highest potential ditference,'and the parts of high potential difference along the stack between its ends, are amply insulated from one another by the insulating casing, thereby obviating -all the prior difficulties in metalcased stacks, as to insulating the high potential terminal from the metal casing, and in preventing the metal casing fromtoo close electrical relation with the points of high po casing providing an extended creepage distance between the condenser ends of high potential difference.

4. A high tension electrical condenser com prising a slicetstacl-: consisting of a plurality of serially-connected stack sections; a tubular casing of insulating material extending around the sides of the stack and having end openings in the vicinity of the ends of the stack; metal end structures held to said insulating casing and closing the ends thereof, one end of the stack abutting against one of said end members; and a staclcclamping de- \lCB located inside the casing between the other end of the stack and the other of said end structures, said clamping device compressing the stack against the first. end structure and holdin; the staclnsheets in intimate contact with one another; and said second end structure transmitting clamping tension to the tubular insulating casing.

5. A high tension electrical condenser comprising a sheet-staclt consisting of a plurality of serially-connected stack-sections; a tubular casing of insulating material extending around the sides of the stack and havingend openings in the vicinity of the stack-ends; two metal condenser terminals held=to the" respeetive ends of the casing, electrically connected to the correspondingstack-ends inside the casing, and extending through said casing-openings; one end of the"stack-ahutting against one of said terminals; and a metal member adjustably mounted in the other terminal, holding the stack-sheets in intimate contact with one another successivel)", and holding said insulating tuhulancasing under tension via said terminaL- (3. A high tension electrical condenser} c mprising sheet-stack consisting of aplurality of serially-connected stack-sections; an insulating casing extendingaronnd the sides of. said stack; a clamping member located inside. said casing, engaging one end of the stacl'. and holding the stack-sheets inintiu'iate contact with one another successively, and a metal end structure held to the casing. engrzr a said stack clamping; memher, and transmitting clamping tension to the insulating casing.

7. A high tension electrical condenser comprising a sheet-stack consisting of a pluralit} of serially-connected stack sections; an in- Sillfillllg casing extending around the sides of said stack: and a stack-clamping device lorated inside said insulating' casing between ne end of the stack and the casing, and holding the stack under compression and its sheets in intimate contact with one another success-inst said sta -clampin device being meclmnica ly connected with. said insulatin casing thereby putting the insulating easing under the tension stress of the stack clamping.

8. A high tension electrical condenser comprising a sheet-stack consisting, of a plurality of serially-connected stacksections; an insulating casing extending around the sides of said stack, and having an end opening adjacent an end of the stack; a metal end structure fixedlyheld to said casing and closing said opening; and a metal compressing member engaging said stack-end and in movable relation with said end structure, holding the stack under compression and the insulatin casing under tension.

9. A high tension electrical condenser com prising a sheet-stack consisting of a plurality of serially-connected stack-sections; a casing of insulating material extending around the sides of the stack, forming an enclosed space around said stack-sides; a stack-clamping device located inside said insulating casing between one end of the stack and the casing, mechanically connected with the insulating casing thereby putting it under sta'ck-clamping tension; and a readily fusible insulating embedment filling said enclosed space between the stack and insulating: casin 10. A high tension'= -electrical condenser comprising a sheet-stackconsistingiof'a pluralityof serially-connected stack. sections; an insulat-ing casing extending around the sides of said stack5 andliaving an end openingadjacent an end of the stack; a metalendstructur fixedly heldzto the casing; a.

metal compression member presing the.cor-. responding end of'the stack;:-and a metal. compression-adjusting member inovably en-- gaging said end member and pressing said compression 'memher againstthe s'tack and holding the stack-sheets in intimate'eontact with one another successively; said inetal end structureheld to'thecasing holding the lat-; terunde'r tension; ii P 11. A high tension electrical condenser comprising a sheet-stack'consistingof a. plu rality of seriallywonnected 'stack-sections;-'a-

casing ofinsulating 'material';fextending;

around the of tli'stack. andhaving-an eud'opening in the vicinity of an end of the stack; a metal endstru'ctureheld to said insnlat-ing casing; andrnetallic. means adj 11stable. in said end structure,' holding the stacksheets in intimate contact with one another successively; said metal end structure held to the insulating casing holding the latter under tension established by said-adjustable member.

12. A high tension electrical condenser comprising a sheet-stackconsisting of a plurality of serially-connected stack-sections; a tubular casing of insulating-material extending around the'sides of'the stack; a metal end structure held to said casing and closing anend thereof, one end of the stack abutting against said metal end structure; and a stack-clamping structure engaging the other end of the stack, compressing the vstack against said metal end member, and holding stack, the side-walls of the casing lying ad-.

the stack-sheets in intimate contact with one another successively.

13. A high tension electrical condenser comprising a sheet-stack consisting of a plurality of serially-connected stack-sections, a casing of insulating material extending around. the sides of said stack, and a stack con'ipressor located inside the casing and ac;- ing on the end of the stack to hold the stack sheets in intimate contact with one another successively, said stack-compressor being mechanically connected with the insulating casing, thereby putting' said casing under stackcli'iln'iping tension;

14'. A high tension .electrical condenser comprising a sheet-stackconsisting of a plurality of serially-connected stack-section's; a casing of insulating material extending around the sides of said stack; and means, of which said insulating casing is a part, for holding the stack-sheets in intimate contact with one another successively, said means comprising a sta'ck coi'npres'sing member holding the insulating casing under tension.

15'. A high tension electrical condenser comprising a sheet stack consisting of a plurality of serially-connected stack-sections; a casing of insulating material extending around the sides of said stack; a metal-end structure held to an end of said casing; and a member located between an end of the stack and said metal end structure, holding the insulating casin under tension and the stack under compression.

16. A- high tension electrical condenser comprising a plurality of serially-connected stack-sections arranged in a stack having oppcsite potential ends; a casing enclosing said jacent the sides of the stack and consisting of insulating materialiformed integrally in one piece; the ends of,the casing including opposite potential condenser terminals held to the insulating casing-walls, electrically connected to the ends of the stack and insulated from one another by the side walls of the casing.

17. An electrostatic condenser comprising dielectric and conducting sheets; a casing of insulating material extending around the condenser and having an end opening in the vicinity of a portion thereof; a metal end structure located at said end of the insulating casing, secured thereto, and closing said casing opening; and an adjustable metal stack-clamping .device mechanically connected ivith said metal end structure whereby the latter.. by its mechanical connection 'with the insulating casing, puts said casing under tension when the adjustable clamping device is operated to compress'the condenser. 18. An electrostatic condenser comprising a stack of dielectric and conducting sheets; an insulating casing extending around the sides of said stack and having end openings in the vicinity of the stack-ends; clamping means secured to one end of the insulating casing and thereby transmitting the tension strain of stack-clamping vto the insulating wall of the casing: said clamping means being electrically connected to a part of the condc 'iscr; and a metal conducting path elcctrically connected with a part of the coin denser of different potential and extending thru the other end opening of the insulating usv 19. A high tensionelectrostatic condenser comprising a plurality of serially connected condenser-sections arranged directly adjacent one another in a single stack having a high potential difference across its ends; a casing of insulating material extending around the sides of said stack from end to end thereof and having opposite end openings adjacent the ends of said series-sectional stack; a metal end structure closin one end opening of said casing and meaia nically supported thereby, said end structure being electrically connected with the adjacent end section of the stack and subjecting the stack to high mechanical compression; and a second terminal located at the other end of the stack and insulating casin electrically connected with the sec tion of the stack at that end ,thereof, and extending thru the opening in that end of the insl ilating casing, said casing electrically separating from one another said terminals of high potential difference.

20. An electrical condenser comprising sheets of dielectric and conductors and a caring therefor, the side walls of which are of insula.ting -material and extend around the sides of said condenser; the ends of the casing being adjacent the ends of the condenser and including metal parts between which the condenser is compressed, and mechanically secured to the insulating side walls thereby transmitting tension strains of clampingthereto. said metal ends being electrically and thermally connected to opposite potential parts of the condenser, and formed with heat dissipating projections at their portion's' outside the casing. I

21. A clamped and enclosed construction for electrostatic condensers which compris a casing for the condenser having an insulating portion and a metal portion, the insulating portion extending around the condenser and constituting a tension member of the condenser clamping system and the metal portion of the casing constituting a compression. member of the clamping system, being mechanically connected withthe insulating casing-portion to cause the latter to take the tension strains of the condenser compression. I

' 22. A clamped andenclosed electrostatic condenser stack construction in which the tension member of the clamp coifipre'ssiiig its sheets in planes parallel with said opening; a metal structure covering said opening and secured to the insulating casing; and a condenser compressor mounted in said metal structure and adjustable toward the flat end of the condenser; said metal casingcover, by its connection with both the condenser compressor and the insrlat-ing casing, serving to include the latter as the tension member of the mechanical system by which the condenser is held under compression,

24. An electrostatic condenser structure which comprises a condenser including dielectric and armature sheets and electrical connections of opposite potential extending laterally of the condenser from its armatures; a casing of insulating material extending around the condenser laterally; a condensercompressor located inside the insulating casing and holding the condenser sheets in intimate contact with one another successively; and means connected both with the insulating casing and the condenser-compressor and causing the insulating casing to-be the tension member of the mechanicalsystem by which the condenser is held under compression.

25. An electrostatic condenser structure which comprises a condenser including di electric and armature sheetsand electrical connections of opposite polarity extending from the arnia-tures, and a casing inand by which the sheets of the condenser are clamped together and which completely encloses the condenser; said casing consisting of an insulating port-ion surrounding the lateral portion of the condenser and thereby preventing interference with oneanother of the opposite potential connect-ions: said casing also consisting of two metal end structures secured to said insulating casing-portion, located in compressing relation with the' condenser sheets. electrically connected, as opposite potential circuit terminals respectively, with said opposite potential electrical connections, and electrically separated from one another by said insulating casing-portion; the mechanical connections of said condenser-compressing .meta-l port-ions with the insulating portion of the casing constituting said insulating portion as the tension member of the mechanical system holding the condenser under compression.

26. The combination with an'electrostat-ic condenser stack, of two metal end structures respectively located at the two end faces of the stack; a tubular casing of insulating material extending around the sides of the stack, having end openings in thevieinityof the stack ends, and having its ends mechanically connected with the respective metal end structures; one of said metal end structures including an adjustable stack-compressing member which has a mechanical connection with the rest of the metal end structure which connect-ion includes threaded metal pressure applying means located at a compressing angle with said adjustable con'ipressing member: the metal end structure which includes said adjustable compressing member including also threaded tension means of metal engaged by said threaded metal pressure applying means; all whereby the screwing up of the threaded metal pressure applying means causes the metal tension means to put the insulatingcasing under tension when the stack is compressed between the adjustable compressing member and the metal end structure located at the opposite end of the stack.

27. An enclosed high tension electrostatic condenser construction which comprises a condenser casing of insulating material having oppositely disposed openings; a condenser in the form of a stack of sheets and positioned in said insulating casing as have its 'sides extending along the insulating wall of the easing and its opposite'ends in the vicinity of said casing-openings;- said stack being di "ided by insulating separators into sections, and said sections being electrically'connected inseries with one another by armature-connections located out-side the stack at the sides thereof and facingthe wall of the casing, whereby there is a potential difference across the ends of each section and a high potential difference across the ends of the stack of sections; and twoeondenser tenninals of opposite potential connected with the armatures of the two end sections of said stack and extending thru the opposite openings of the i nsulating easing; said casing extendingfrom end to end of the stack and from one of said condenser terminals to the other, and'preventing electrical interference of any of the stacksections with one another or with any metal parts, and providing wide electrical separation entirely around the stack of the opposite stack ends and of said condenser terminals of high potential difference.

28. An enclosed high tension electrostatic condenser construction which comprises a condenser casing of insulating material'having oppositely disposed openings: a condenser in the form of astack of sheets and positioned in said insulating casing to have its sides extending along the insulatingwall of the easing and its ends in the vicinity of said casing openings; said stack being divided by insu: lating separators into sections and said sections being electrically connected in series with one another by armature-connections located outside the stack at the sides thereof and facing the wall of the casing whereby there is a potential difference across the ends of each section; and two condenser terminals connected with. the armatures of the two end sections-of said st-aclr and extendingthru the opposite openings of said insulating casing;

- said insulatingcasing.- extendingfrom end to en(l'of=tlic stack, fromone of said condenser terminals to the. other and entirely around the sides of the stack and preventing electrical interference of any of the stack sections with one another or with any metal parts.

29. A'high potential condenser unit comprising a plurality ofrelatively low potential condensers arranged face to face with one another in a unitstacl; as closely adjacent together as desired for compactness, the oppositely poled armature terminals of the individual condensers projecting laterally from the unit stack, the armature-terminals of like polarity of adjacent individual condensers being connected together permitting the laterally projecting armature-terminals of un-' like polarity of the same adjacent individual condensers, and lying at separated points alongthe length ofthe unit stack, to be subjected to relatively high potential differences; in combination with an encasingmeans for such unit stack which means includes a member of structural insulating material extending from end to endof the stackalong the sides of all= the individual condensers and surrounding said sides ci-reumferentially and as closely adjacent as desired for compactness to saidlaterallyprojecting armatore-terminals of relatively high potential difference; whereby all of the plurality of individual condensers are provided with a single common protective casing member of structural material which is non-conducting between all points ofhigh potential difi'ercnce between" the ends and along the sides of the unit stack and adjacent said insulating member.

30. The improvement inelectrical condensers which comprises, in combination with a condenser desired to be compressed and enclosed and to have its terminals insulated from one another,- an enclosing casing which includes as principal member an elementconsist-ing of structural in:;--uIat-in; material extending circumferent-ially around the condenser between its terminals, :1 portion of the enclosing casing being abut-ted by a portion of the enclosed condenser: and condenser clamping mechanism including at least two members having threaded cngagen'ient with one another, one being movable toward the enclosed condenser to compress the latter against the casing portion which it abuts,- and the other being mechanically connected with the insulating member of the casing and subjecting its circumferential extent around the condenser to the stress resulting from the compression of the enclosed stack.

31. The improvement in electrical condensers which com-prises, in combination neaeaaeo with a condenser desired to be compressed and enclosedand to have its terminals insulated from one anothen, an enclosing casing which includes as principal member an element consisting of structural! insulating ma-' terial extending circumferentially around the condenser between its terminals, a portion of the enclosing casing being abutted by a portion of-the enclosed condenser; and. condenser clamping mechanism including at least three members of: which two-are movable toward the condenser to compress the latter against the casing portion which itabuts and the other is mechanicallyconnected with said two and with the insulating member of the casing subjecting the circumferential extent. of the latter around the condenser to the stress resulting from the compression of the enclosed stack.

32. The improvement in electrical condensers which comprises, in combination with a condenser desired to be compressed and enclosed and to have its terminals insulated from one another, an enclosing. casing which includes as principal member an element consisting of structural insulating material extending circumferentially around the condenser between its terminals, a portion of the enclosing casing being ahutted by a portion of the enclosed condenser; and condenser. clamping mechanism including at least two members of which one is movable toward the condenser to compress the latter againstthe casing-portion which it abuts and the other is mechanically connectedwith the first and with the insulating member of the casing subjecting the circumferential extent of the latter around the condenser to the stress resulting from the compression of the enclosed stack.

33. The improvement in electrical con densors which comprises, in combination with a condenser desired to be compressed and enclosed and to. have its terminals insaluted from one another, an enclosing casing which includes as principal member an element. consisting of structural insulating material extending circumferentially around the condenser between its terminals, 9. portion of the enclosing casing being abut-ted by a portion of the enclosed condenser; and condenser clamping mechanism including at least three members of which the first engages the condenser opposite the port-ion of the condenser which abuts the enclosing casing. the second is secured to the insulating portion of the casing subjecting its circumferential extent around the condenser to the stress of the condenser compression by the first. and the third is threaded and thereby has mechanical connection with the second. said third member being movable on its threads to engage the first member to coinpress the condenser, said movement subjecting the insulating casing-member to said stress by way of the mechanical connection between the third and second members.

34. The improvement in electrical condensers which comprises, in combination with a condenser desired to be enclosed, to have its terminals insulated from one another and to have heat removed from its interior and dissipated outside the enclosure, an enclosing casing which includes as principal member an element consisting of structural insulating material extending circumferentially around the condenser between its terminals; a metal end structure completing the condenser enclosure at one end of said insulating member and having a substantial externally exposed heat-dissipating surface; and means conducting heat to such surface from the interior of the condenser, said means including a metal lead of substantial crosssectional area located inside the casing and secured in good thermal connection with the armatures of the condenser and with said metal end structure.

GREENLEAF WHlTTlER PICKARD. 

